1,3-butadiene can be prepared by performing contact oxidative dehydrogenation for monoolefins, such as n-butene, in the presence of a catalyst.
U.S. Pat. No. 4,595,788, which is an example of existing technologies of collecting hydrocarbon containing butadiene from a reactive gas mixture including 1,3-butadiene generated by contact oxidative dehydrogenation, discloses a technology of absorbing most of a C4 ingredient including butadiene before isolation of crude butadiene, and degassing remaining gas and then circulating the same in a reactor.
In accordance this technology, a portion of a light byproduct (light carbonyl, compound having boiling point of 100° C. or less and carbon number of 4) included in the generated gas and most of a heavy byproduct (heavy carbonyl, compound having boiling point of 100° C. or less and carbon number of 5 or 6) are removed by being absorbed into a cooling tower. However, most of the light byproduct and the portion of the heavy byproduct are subjected to a stripping process performed as a subsequent process. Accordingly, after the stripping, the light and heavy byproducts should be subjected to post-treatment, and some of the light byproduct may react with the butadiene included in the generated gas to function as a cause of butadiene loss. In addition, a general biological waste water disposal equipment required due to an excessive content of byproducts contained in water discharged from the cooling tower is a heavy burden. Accordingly, there was an attempt to feed an aqueous alkaline solution, fresh water, etc., as a cooling solvent, into the cooling tower such that an excessive content of byproducts in water discharged from the cooling tower is reduced. However, slurry was formed and fouling was generated due to a solid-phase salt and a heave material with a boiling point of 100° C. or more, which are generated upon feeding of the aqueous alkaline solution. In addition, the amount of waste water greatly increased upon feeding of the fresh water.
Therefore, there is an urgent need for technology of treating water discharged from the cooling tower while increasing process efficiency.